The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An airplane is driven by several turbojet engines each housed in a nacelle also harboring an assembly of ancillary actuation devices related to its operation and ensuring various functions when the turbojet engine is operating or at a standstill, such as for example a thrust reversal system.
More specifically a nacelle generally has a structure comprising an air intake upstream from the engine, a middle section intended to surround a fan of the turbojet engine, and a downstream section intended to surround the combustion chamber of the turbojet engine and harboring thrust reversal means.
The fan of the turbojet engine essentially consists of a rotary shaft bearing a plurality of blades. At their radial end, the blades are circumferentially surrounded by a case.
In order to be able to access the case of the fans, the middle section generally comprises at least two cowlings capable of radially opening by pivoting around an upper longitudinal hinge line located in proximity to an axis of the pylon to which the nacelle has to be attached.
In the closing position, these cowlings are locked on a fixed structure or with each other by a set of locks, along a lower longitudinal locking line in the case of a driving installation under a wing.
The presence of these cowlings in the middle section has an impact on the load spreading paths between the structures of the nacelle and on the transmission paths of the latter towards the pylon since the main force transmission lines are localized along the hinge line and the locking line.
Such a configuration is not optimum in the case of circumferential forces which have to be contained, notably for example in the case of an incident of the blade loss type.
More specifically, in the case of a blade loss, the air intake is subject to significant displacements associated with significant loads. Conventionally, these loads are spread out by the fan case via a fan case/air intake connecting bracket.
Complementarily, it may also be noted that an opening mode by pivoting may have difficulties when the nacelle is close to the structure of the airplane, and notably of the wing. Indeed, during maintenance interventions on the turbojet engine, the half-portions and cowlings of the nacelle which are located in proximity to the wing cannot be opened beyond a certain angle, the latter being blocked by the wing or more generally by the structure of the airplane.
Further, radial opening of the cowlings requires the presence of powerful opening actuation cylinders inside the nacelle, these actuators having to be able to support the weight of the cowlings as well as the forces due to gusts of wind on the ground or half-portions as well as of connecting rods allowing these cowlings and half portions to be secured in the open position. These elements represent a significant weight and occupation space.